This invention relates to nitrous oxide fuel systems for fuel injected internal combustion engines, and, more particularly, to a nitrous oxide plate system for fuel injected engines that enables more rapid generation of more horsepower and optimizes balance of the engine cylinders.
Many automobile enthusiasts labor long and hard to ensure that their prize possession, their automobile, is able to make a respectable showing in competitive quarter mile races. To accomplish that objective, the enthusiast needs to ensure that the automobile engine is able to rapidly generate the highest horsepower possible of which the engine is capable in the shortest time.
In a conventionally fueled internal combustion engine, vaporized fuel, such as gasoline or alcohol, is introduced through a carburetor and mixes with air drawn into the engine manifold to form a combustible mix. The combustible mix is drawn through an intake runner of the manifold and, ultimately, into a cylinder of the engine in which the combustible mix is ignited by the spark produced at the spark plug in the cylinder. The resultant explosion inside the combustion chamber of the cylinder produces the mechanical force on a piston. The forced movement of the piston is ultimately mechanically transferred through the transmission to the wheels of the automobile, which propels the automobile. That combustion process repeats for each cylinder in the engine.
A fuel injected engine, on the other hand, doesn""t employ a carburetor to form the combustible fuel and oxygen mix. Instead, the outside air is drawn into the engine through an air intake manifold and is individually distributed to the multiple engine cylinders by individual intake air runners. Fuel injectors are located in the runner near the intake valve of the respective cylinders. The injectors receive fuel via a fuel line. At the appropriate point in the engine cycle, the injector associated with a given cylinder injects a measured amount of fuel into the associated intake runner at a location adjacent the cylinder. That injected fuel mixes with the air drawn to that region through the runner to form the combustible mix, which is drawn through an open intake valve into the cylinder combustion chamber. During the compression cycle, that mix is ignited by the cylinder spark plug. The force of the resultant explosion in the cylinder drives the cylinder piston. Typically the multiple fuel injectors in a multi-cylinder engine are individually computer controlled, which provides much better control of combustion than available with those engines employing carburetors. It is noted that fuel is not always present in the intake runners during engine operation as is the case with engines that employ carburetors. Instead the combustible mix is present in a runner for only a short interval and in a very limited region of the runner.
In either system, the proportion of oxygen in a given volume of air relative to the other components of the air, such as nitrogen, is relatively fixed. Typically, through proper carburetion or fuel injection, the ratio of oxygen and fuel in the explosive mixture is set to the optimal ratio known to achieve the most efficient explosion. To enhance performance in automotive racing application beyond that possible with conventional fuel systems of the foregoing type, racing enthusiasts learned to inject nitrous oxide (xe2x80x9cN2Oxe2x80x9d) into the cylinders along with the combustible mix introduced by the carburetor or fuel injectors and accompany the nitrous injection with an added injection of additional fuel.
Air typically contains about 15% oxygen (by volume) while Nitrous Oxide contains 33% oxygen. When heated to elevated temperatures available within the engine during combustion, the nitrous oxide decomposes into molecules of nitrogen and oxygen gases. Oxygen is thereby released and added to the oxygen in the air introduced through the runner. That additional oxygen enriches the combustible mix in the cylinder. To a limit, the greater the percentage of oxygen in the combustible mixture, the stronger the resultant explosion when the mixture is ignited. Therefore, when nitrous oxide is included as part of the combustible mixture, the power of the explosion is greatly increased, producing increased horsepower from the engine. The additional fuel accompanying the nitrous oxide prevents the combustible mixture from becoming too lean as could cause overheating and damage to the engine. As an advantage, a nitrous oxide system may be used in stock engines without requiring expensive engine modification.
Two principal techniques for introducing the nitrous oxide are currently in use. One is by injection of the nitrous oxide directly into the intake runners of the engine. The other technique is injecting the nitrous oxide into the plenum of the intake manifold.
The first, often referred to as a nitrous nozzle system, employs multiple nozzles, each containing a pair of outlets for individually expressing both nitrous oxide and fuel. Each nozzle is placed directly into a respective one of the intake runners and is connected to nitrous and fuel lines. When the nozzle system is activated during engine operation, nitrous oxide and fuel are introduced into a respective runner by the nozzle associated with that runner. The nitrous oxide is stored in a canister under high pressure and in liquid form. When the nitrous oxide is expressed from the nozzle, the nitrous changes from the liquid state to what is said to be a predominantly gaseous state. The vaporized nitrous oxide essentially impacts at high velocity the fuel simultaneously being expressed. The force of impact atomizes the expressed fuel and the nitrous oxide mixes with that fuel. That mixture merges into the combustible air/fuel mixture being drawn into the intake runner through the carburetor. The nozzle system is considered the optimal technique for delivering nitrous oxide to the engine. A recent nitrous nozzle system, as example, is presented in U.S. Pat. No. 6,520,165, granted Feb. 18, 2003 to Steele, entitled xe2x80x9cNozzle for Emitting Nitrous Oxide and Fuel to Enginesxe2x80x9d.
The second technique is referred to as a nitrous module or, as variously termed, a nitrous plate system. The nitrous plate system employs a generally flat rectangular or square metal plate that contains a central opening or passage through the thickness of the plate that is sized to match the plenum of the intake manifold, and at least one pair of spray conduits that extend across that central passage. The plate is sandwiched between the carburetor and the plenum of the intake manifold of the engine. The spray conduits respectively introduce the nitrous oxide and fuel into the intake manifold plenum. In operation, nitrous oxide and fuel are applied through respective passages in the plate and into the ends of the respective spray conduits, where the respective fluids are expressed through the jets or small spray holes in the side of the conduits into the central opening to merge with the combustible air/fuel mixture being drawn through the carburetor. One nitrous plate system is described in U.S. Pat. No. 5,839,418 to Grant entitled Dual Stage Nitrous Oxide and Fuel Injection Plate, granted Nov. 24, 1998 (the xe2x80x9c""418 Grant patentxe2x80x9d). A more improved plate system appears in the copending application of Chestnut, the present inventor, and Lowe, Ser. No. 10/039,839, filed Oct. 26, 2001, entitled Nitrous Oxide Plate System for Engines.
Both the nozzle and the plate system include a liquid flow restrictor or calibrator, generally referred to as a jet orifice or, simply, jet to restrict the respective nitrous oxide and fuel flow rates through the respective nozzles and the spray conduits of the plate. Those jets are installed in-line with the respective nitrous oxide and fuel lines, typically inserted in the fitting. The size of the orifice in the respective jets regulates the amount of nitrous oxide and fuel introduced through the spray conduits, and, thereby, regulates the level of horsepower attained from the engine. The jets also regulate the nitrous oxide to fuel ratio of the mixture, which is critical to avoiding engine damage. Jets are commercially available in a variety of hole diameters for use in all types of nitrous oxide systems. Accordingly, the racing enthusiast is able to select different horsepower levels by changing the jets in the manner recommended by the manufacturer.
Because the nozzle system uses individual nozzles for individual engine cylinders, a pair of jets is used for each nozzle, one for the nitrous oxide and the other for the fuel emitted from the nozzle. Using temperature sensors to monitor the temperature of each engine cylinder, one can determine if a cylinder is producing too much horsepower, that is, the exhaust gas is running too hot relative to the other cylinders, and can determine whether the cylinders are providing the same horsepower, that is, the cylinders are running at the same temperature, and, hence, are balanced. If one engine cylinder appears weak relative to the other cylinders, it is possible to change the size of the jets associated with the nozzle for that cylinder, typically the one for the nitrous oxide, to increase the strength of the combustible mix in that cylinder. Conversely, if one cylinder has a combustion strength greater than the others, and, consequently, is running hotter than the other cylinders, it is possible to replace the jets with other jets that have a smaller diameter orifice, which weakens the explosiveness of the mix.
In the foregoing way, the performance of the engine cylinders are individually xe2x80x9ctunablexe2x80x9d so as to achieve balance between cylinders, intended to produce maximum horsepower while avoiding engine damage. That tunability is an advantage of the nozzle type system. The plate system, however, does not possess that tunability. Although the prior plate system described in the copending application of Chestnut and Lowe, Ser. No. 10/039,839 provides some tunability for pairs of cylinders, the structure is inherently incapable of individually tuning cylinders.
Historically, the nozzle system attained superior results over the nitrous plate system. As a result, the nozzle system achieved wide acceptance among racing enthusiasts. An impediment of a political nature, however, faces racing enthusiasts who use that system. For reasons, which may be partially explained by the effectiveness of the nozzle system, the various racing associations refuse to permit the use of the nozzle system in several classes of drag racing. That prohibition limits many racing enthusiasts to use of the plate system in their automobiles.
The plate system has also been adapted to fuel injected internal combustion engines. A highly regarded fuel injected engine of that type is the Ford 5.0 liter V8 engine, such as those used in the Ford Mustang automobiles for model years 1986 through 1995. The air intake manifold for that engine is a two-piece structure that contains upper and lower intake members, a somewhat unique structure. The two intake members are bolted together in place over the collection of individual air intake runners associated with respective ones of the eight cylinders of the engine. The upper intake member contains the air inlet for drawing in the outside air and the lower intake member contains an air inlet that mates with the respective air outlet of the first member and couples the air inlet to the air outlets to all eight intake runners to the engine.
The Nitrous Oxide Systems company produced a nitrous oxide plate system for the foregoing Ford V8 engine, which appears at page 19 in that company""s 2001 catalogue. That plate system includes an elongate metal plate member containing eight ports, one for each of the intake runners, and two pairs of metal spray conduits, one spray conduit in each pair for nitrous oxide and the other in each pair for fuel. One pair of the nitrous oxide and fuel spray conduits extend through each of the four adjacent ports to the right of the plate center in a direction along the longitudinal axis of the plate. The second pair of those spray conduits extend through the remaining four adjacent ports to the left of the plate center also in a direction along the longitudinal axis of the plate. A fitting, which includes a jet, is connected to the input end of each spray conduit to connect the respective conduits to the nitrous oxide and fuel supplies, respectively, carried in the vehicle. For operation, the foregoing plate is sandwiched in between the upper and lower manifold members and those elements are bolted together to the engine.
In operation, the nitrous oxide and fuel are respectively supplied and/or pumped into the respective spray conduits. In turn, the spray conduits emit the respective sprays of nitrous oxide and fuel through small jets or openings in the cylindrical wall of the spray conduit into each of the eight ports providing a nitrous and fuel mix for each. The air being drawn into the engine through the intake manifold (and sandwiched nitrous plate) draws the nitrous fuel mix through the respective runner during the intake cycle for the respective cylinder of the engine producing a nitrous fuel and air mixture. The fuel injector injects the normal measure of fuel into the end of the respective runner near the intake valve of the cylinder at the appropriate interval, where that injected fuel mixes with the mixture of air, nitrous oxide and fuel for collective application in the combustion chamber of the cylinder. Like the plate systems for engines that employ carburetion, the nitrous oxide and fuel introduced by the plate is present in the length of the respective runners.
The foregoing plate system of the Nitrous Oxide Systems company is not without a drawback. Even or balanced distribution of the added nitrous oxide and fuel mixture amongst all of the engine cylinders is a key factor in the use of the plate system. However, the foregoing plate system does not always evenly distribute the nitrous oxide and fuel amongst the individual intake runners of the manifold. Nor does that nitrous plate system posses the desired tuneability. That system contains a jet for each of the nitrous oxide and fuel spray conduits in each of the two pairs of spray conduits, and each pair of those conduits serve a respective four of the eight ports in the plate. Thus, if an individual one of the eight engine cylinders is too weak or too strong, changing the size of the orifice in the jet for the nitrous oxide conduit associated with the weak cylinder, as example, changes the flow rate of the nitrous oxide into the three remaining cylinders serviced by that conduit as well. As a consequence, some of those four cylinders of the engine receive more or less of the powerful nitrous fuel mix than the others, producing an unbalance in the combustion power. That imbalance not only detracts from engine performance, but could potentially be harmful to the internal components of the engine. Tinkering with the fuel injection to adjust the fuel injected in one or more cylinders could aid in adjusting balance between the cylinders, but that procedure is not recommended as changing the injector mapping in the electronic control module is very costly and, when the engine is not running with the nitrous oxide, the fuel delivery to the engine cylinders is uneven. As an advantage the present plate system is tunable.
Further, since each of the two pairs of spray conduits of the foregoing nitrous plate system respectively spans the length of four of the eight ports in the plate, when the respective solenoid valves in the automobile open to permit the nitrous oxide and fuel to enter one end of the respective spray conduits, those liquids flow into and toward the opposite end of the respective conduit. Although the nitrous oxide is under a very high pressure, some very small but finite interval of time is required for the initial flow to reach the end of the spray conduit and permit the respective spray conduits to express nitrous oxide evenly from the spray holes positioned over each of the four ports. Inherently, the ports at the inlet end of the spray conduit receive the nitrous (and fuel) spray first and the fourth port in the group of four ports receives the nitrous (and fuel) spray last. That results in an unavoidable lag in developing the horsepower available from the engine.
The consequence of the initial flow of nitrous oxide into the spray conduit has been thought to be a possible source of some of the distribution problem experienced by users. Some have speculated that liquid nitrous oxide under high pressure is capable of vaporizing from the liquid state in the short time that is taken for the initial flow to span the distance from one end of the spray conduit to the other. Thus, those spray holes lying over the fourth port may be spraying a gas, while the ports closest to the first port will be vaporizing the nitrous oxide at the spray hole. This is believed to create some imbalance in the volume of nitrous oxide expressed, at least initially, until the fluid stabilizes.
Therefore, a principal object of the invention is to improve the distribution of nitrous oxide and fuel in nitrous plate systems for fuel injected internal combustion engines and increase available horsepower in those engines.
A further object of the invention is to reduce start up lag in a nitrous plate system for a fuel injected engine and thereby enhance acceleration of the engine.
A still further object of the invention is to provide a nitrous plate system for a fuel injected engine that permits tuning of the individual cylinders of the engine.
And a more specific object of the invention is to provide a nitrous plate system that enhances the horsepower available from a Ford 5.0 liter V8 engine without requiring modification of the engine.
In accordance with the foregoing objects and advantages, a tunable nitrous plate assembly for a fuel injected Ford 5.0 liter V8 engine in accordance with the invention includes a metal plate that is adapted to be sandwiched between the upper and lower manifold members of the air intake manifold for the engine. The plate contains multiple ports that mate with the ports found in the lower manifold member. Each of those ports includes a nitrous oxide spray conduit overlying a fuel spray conduit, both supported by the plate, and both spray conduits extend across the port transverse the longitudinal axis of the plate. The conduits contain an open end that opens into a respective passage through a side of the plate to the exterior. A fitting attaches to the outside of the metal plate and communicates through one of the passages with the open end of the nitrous oxide spray conduit to provide a path for the flow of nitrous oxide into the respective spray conduit. Another fitting attaches to the outside of the metal plate and communicates through the other passage with the open end of the fuel spray conduit to provide a path for the flow of fuel into the respective spray conduit.
Further, in accordance with an aspect of the invention, each fitting houses a jet and is adapted to couple to a respective nitrous oxide or fuel supply line. The jets are replaceable to permit the user to individually select a size for each port so that the horsepower developed by each engine cylinder during operation is essentially the same, that is, tune the nitrous plate system and balance cylinder performance.
In accordance with a more specific aspect of the invention, the spray conduits each contain two spaced parallel rows of spray holes extending parallel to the spray conduit axis with an equal number of holes in each. The spray holes in one spray conduit are axially aligned with those in the other spray conduit. The rows of spray holes in the spray conduit for the fuel are spaced one-hundred and eighty degrees apart about the conduit axis. The rows of spray holes in the overlying spray conduit for the nitrous oxide are spaced apart about sixty degrees about the conduit axis. The two conduits are angularly oriented so that the rows of spray holes in the two conduits are angularly symmetric and the spray holes in the spray conduit for the nitrous oxide facing downwardly at an angle into the port.